The most earthquake-prone zone in the world is Alaska. It is one of the most seismically active zones in the world. Alaska experiences a magnitude eight or greater earthquake every fourteen years, and a magnitude seven earthquake almost every year.
On March 27, 1964, the largest recorded earthquake struck Prince William Sound, Alaska, in the United States of America. The magnitude of the earthquake was 9.2 on the Richter scale.
The first earthquake in America was experienced in 1663 by the European settlers. Florida and North Dakota record the smallest number of earthquakes in the United States of America.
Formation of a Tsunami
A tsunami is generally formed as a result of plate tectonics where sudden movement of plates displaces the water above it, eventually giving rise to a series of powerful water waves. Scientifically, it is generated when an overriding plate of the plate boundaries (divergent or convergent) develops a bulge over a number of years.
This bulge slips after the stress on the plates exceeds beyond the normal amount. This affects the energy of water that is in direct contact, generating a tsunami. The same is observed in the case of normal faults too, however the chances of formation of a tsunami in such cases are slim.
The largest recorded earthquake in the world was in Chile in 1960. The magnitude of the earthquake was 9.5. During the Chilean earthquake, the seismic waves traveled around the globe for many days. This is known as free oscillation of the Earth.
The earthquake that occurred in central China in 1556 is the world's deadliest quake ever. The quake struck a region in China where most people lived in caves carved out from soft rock. These caves collapsed during the earthquake, killing over 830,000 people.
Another deadly earthquake struck Tangshan, China in 1976, killing an estimated 250,000 people.
The Pacific Plate is known as the Pacific Plate of Fire because it is one of the most active plate boundaries where earthquakes as well as eruptions are frequent.
The earliest earthquake was recorded in the Shandong province of China back in 1831 BC.
The Southern Californian region has about ten thousand earthquakes every year. However, many of them are small and are not felt. Rarely any of them are above magnitude three and a few are above magnitude four. Therefore, earthquakes occur almost every day in California. Such earthquakes also occur in Indonesia, Japan and Azores in Portugal.
It is said that in Australia, an earthquake that measures 5.5 on the Richter scale occurs every 15 months on an average. The western and central parts of Australia, are the most seismically active areas.
Therefore, 'magnitude' is the quantitative expression of the earthquake, while the shaking capacity of the earthquake is called 'intensity'.
The location below the Earth's surface, where the rupture of the fault begins is known as the hypocenter. The point directly above the hypocenter on the surface of the Earth is known as the epicenter.